lee1 writes: ""Imagine the confusion, inconvenience, and possible embarrassment that could be created if the operator of an smtp server decided, unilaterally and without advertisement, to deviate from the published standards and expected behavior by tampering with your email. Imagine if they silently changed the From: header to a different address; one that belonged to someone else, one that was not supposed to be publicly known, or one that is not monitored? Google does exactly this."